Field of the Invention
The present invention relates to tapered roller bearings used as, for example, wheel bearings, and particularly to a technique for preventing inner ring raceways from being damaged during assembling.
Description of Related Art
When a tapered roller bearing is assembled, rollers and a retainer are previously incorporated into an inner ring, to form an inner ring sub-assembly, and the inner ring sub-assembly is incorporated into an outer ring. As shown in FIG. 8A, an outer diameter ϕd2 of a small collar portion 7 of an inner ring 2 is set to be larger than an inscribed circle diameter ϕd1 of a circle inscribed in arranged rollers such that the rollers or the retainer do not drop from the inner ring sub-assembly, for example, when the inner ring sub-assembly is incorporated into the outer ring or when other handling is performed. The inscribed circle diameter ϕd1 is a diameter of a circle which is inscribed in arranged rollers 4 when an assembly 10 of the rollers and the retainer in which each roller 4 is retained by a retainer 5 has not been incorporated into the inner ring 2. In FIG. 8A, the outer diameter ϕd2 of the small collar portion 7 is enlarged in an exaggerated manner as compared to the inscribed circle diameter ϕd1. However, difference between the diameters ϕd1 and ϕd2 cannot be visually recognized in practice.
To date, for ball bearings, suggestions for preventing dropping of balls and a retainer and preventing damage during incorporation in a case where an assembly of the balls and the retainer is incorporated into an inner ring, have been made (for example, Patent Document 1). However, for tapered roller bearings, similar suggestion has not been made.